1. Field of the Invention
The invention relates to a flexible flat cable, in particular, to a flexible flat cable having a shield layer which is used as a wiring material for transmitting an electrical signal in electronic equipments.
2. Description of the Related Art
In general, a flexible flat cable is widely used as a jumper wire (a fixed wiring) between circuits in various electric and electronic equipments or as a wiring material wired to a movable portion in the electric and electronic equipments in place of a flexible printed-wiring board by taking advantage of plasticity (flexibility) thereof. Particularly in recent years, an application as a wiring material for wiring to a print head portion of a PC inkjet printer or a pick-up portion of CD-ROM drive, car navigation or DVD (Digital Versatile Disc) player, etc., is proceeding.
In recent years, downsizing, weight reduction and multiple functions of electronic equipments have progressed. Therefore, a wiring material which allows high-speed and high-capacity transmission is demanded. Since electrical signal noise in electronic equipments is increased due to transmission frequency, a wiring material having an excellent shielding property is particularly required. Furthermore, the wiring material is required to have characteristic impedance which matches that of the electronic equipment.
As a conventional flexible flat cable having a shield layer which allows characteristic impedance matching, JP-A-2009-170291 discloses a flexible flat cable which is provided with a nonwoven fabric layer provided on an outer surface of an insulation layer and a shield layer provided on an outer surface of the nonwoven fabric layer.